Study On The Synergistic Inhibition Law And Mechanism Of Gas-liquid Two-phase Medium On Gas Explosion In Pipeline

The inhibition and control of combustible gas explosion is a hot issue in the field of industrial safety and public safety.Based on the self-built inert gas-ultrafine water mist inerting suppressing test system on gas explosion in pipeline,this paper carried out a series of gas explosion inhibition experimental researches with single inhibitor and gas-liquid two-phase medium on 9.5%methane/air explosion,to research the influence on overpressure,flame shape,flame propagation speed and maximum flame temperature.The synergistic inhibition law of gas-liquid two-phase medium on 9.5%methane/air explosion was obtained,through analyzing the influence of different kinds of inert gas,the dilution volume fraction and the amount of water mist on the explosion suppression,and the critical parameters of explosion suppression were obtained.Combined with theoretical analysis and the results of numerical simulation,Interphase coupling mechanism between inert gas and ultrafine water mist in gas explosion suppression were also analyzed,and revealed the synergistic inhibition mechanism of gas-liquid two-phase medium on gas explosion,which can provide scientific support for clean and efficient development and utilization of inerting water mist explosion inhibition technology.The inhibition effect of single explosion inhibitor such as inert gas and ultrafine water mist on gas explosion was analyzed.The inhibition effect of inert gas on the flame propagation velocity and explosion overpressure is better than that of ultra-fine water mist,but the cooling effect of ultra-fine water mist on flame temperature is greater than that of inert gas,and to achieve completely inerting the combustible gas that two inhibitors both need relatively high concentrations.The attenuation characteristics of 9.5%methane/air explosion under the inhibition of gas-liquid two-phase medium were obtained,and the influence law of the kind and volume fraction of inert gas dilution,the amount of water mist on the gas-liquid two-phase medium synergistic suppression on the methane/air explosion was obtained,and the key control parameters of gas-liquid two-phase medium to suppress gas explosion are obtained.The results showed that the gas-liquid two-phase medium has obvious synergistic effect on the explosion suppression of 9.5%methane/air premixed gas.In the inhibition of a small amount of inert gas and water mist,the maximum flame propagation velocity and peak overpressure were decreased significantly and their arrival time was also delayed.From the characteristics of the flame shape,compared with the pure water mist condition,the number of cells in the initial flame structure were significantly reduced with a small amount of gas-liquid two-phase medium,even when the control parameters of gas-liquid two-phase medium was greater than a certain degree,the flame image cell disappeared.The flame appeared asymmetric structure,such as"bevel type"or"snake type",which was not conducive to the formation of feedback acceleration between flame and pressure wave.However,the synergistic inhibition effect of gas-liquid two-phase medium on the suppression of 9.5%methane/air explosion is not linearly increased with the increase of the volume fraction of inert gas and the amount of water mist.When the volume fraction of inert gas and ultra-fine water mist were increased to a certain extent,synergistic inhibition effect could be greatly improved;however,the control parameters of gas-liquid two-phase medium continued to increase,the growth rate of explosion suppression gradually reduced.In order to achieve desired effect of explosion control,according to the study of this paper,the control parameters of inert gas and ultra-fine water mist should be with a diluted volume fraction of 14%,the amount of water spray of 8.4mL?mass concentration of 694.4g/m³?.The synergistic inhibition effect of CO₂and ultrafine water mist was the best,but the synergistic inhibition level had little difference between the combination of N₂,He,Ar and ultrafine water mist.18%-CO₂-12.6mL ultrafine water mist?mass concentration 1041.7g/m³?can inert the premixed gas completely.The results showed that gas-liquid two-phase medium not only can improving the inhibition effect,but also reduce the amount of inert gas and water mist,and reduced the restrictions of inert gas species,which is convenient for application in gas explosion inhibition engineering.Through numerical simulation,the distribution of water mist,evaporation rate and gas reaction rate under the effect of gas-liquid two-phase inhibitors were obtained,and clarify the coupling mechanism between inert gas and water mist on the inhibition of gas explosion.The mass transfer and heat transfer of gas explosion flame front were analyzed,and revealed synergistic mechanism of gas-liquid two-phase medium to suppress gas explosion.Under the effect of preferential diffusion,heat sharing and dilution of inert gas,the heat value of premixed gas and laminar flame burning rate were reduced,and the stability of initial flame is enhanced,which decreased the initial flame propagation speed,and allow greater size of droplets and prolonged the residence time of droplets in the flame zone,and lower the droplet evaporation rate,which enhanced the cooling effect of water mist on the flame front,and reduce the pressure rise rate,which indicated the good coupling effect between inert gas and water mist,and its essence was to realize the synergistic inhibition of mass transfer and heat transfer.At the same time,under the congestion and endothermic effect of water mist,the flame appeared asymmetric structure,which caused the asymmetric pressure wave,thereby reducing the compression effect on burned gas,and the acceleration mechanism of mutual promotion between flame wave and pressure wave was weakened.